I might add there are much more scientific ways of doing this using sound level meters and test CDs as some have mentioned above, but the quick method I just described works very good for me.
Once set I keep the crossover point constant for a given pair of main speakers, but I do adjust the subs volume level a bit depending what type of music I am playing and what type of bass I want to hear.
Once set I keep the crossover point constant for a given pair of main speakers, but I do adjust the subs volume level a bit depending what type of music I am playing and what type of bass I want to hear.